三种生物质的热解动力学研究

为进一步研究生物质的热解动力学,在氮气气氛和不同的加热速率下对马尾松、棉杆和杉木试样进行了热分析实验.结果表明,由于生物质中矿物质对热解的催化作用,灰分含量越高,热解温区越低;用占生物质质量约10%的碳酸钠对生物质进行处理后,其热解温区也明显降低;用Ozawa-Flynn-Wall法计算的活化能随转化率的增加而增加,这是由于生物质中不同成分如半纤维素与纤维素等的热解特性不同所致;联合运用Satava法和Ozawa-Flynn-Wall法确定了低温区和高温区热解的最佳机理函数,发现Avrami-Ero-feev方程、Jander方程和Zhuralev,Lesokin and Tempelmen(Z-L-T)方程分别可以用来很好地描述不同温区的热解过程.热解机理是随机成核和随后生长或三维扩散.除了高温催化段以外,在其他温区用两种方法计算的活化能均很接近.     

CoCr2O4纳米晶的制备及其磁性研究

通过高分子金属络合物热解法制备了COCr2O4纳米晶，并对它的表面微结构和磁性能进行了表征。通过高分辨电镜和傅立叶红外光谱的研究发现在平均粒径为12nm的纳米晶表面不仅有晶格炔陷，而且吸附有大量聚合物分解后的有机碎片，这些有机碎片对纳米晶表面磁矩的钉扎以及纳米晶自身的表面晶格缺陷．导致自旋无序的表面和相对自旋有序的核之间产生强的交换耦合作用．从而使得纳料晶呈现出奇特的磁性能，如低温下存在较走的矫顽力和偏置场等。     

聚丙烯热失重特性的研究

采用TG-DTA法研究了聚丙烯在不同气氛下的热失重特性,求取了反应动力学参数,探讨了聚丙烯热失重反应的机理.结果表明,氧气对聚丙烯的失重有明显的促进作用,聚丙烯的热失重反应均符合一级反应模型.     

沉淀-热分解二步法制备纳米氧化锌的试验研究

以氯化锌和碳酸钠为原料，采用沉淀－热分解二步法制备纳米氧化锌，结合TG－DTA热分析，X－射线衍射分析，透射电镜观察等表征手段研究纳米氧化锌粉体的结构和形貌。结果表明，热分解反应因素应因素的影响明显大于沉淀反应，其中热分解温度的影响最为显著。在试验工艺条件下，制备出结晶及分散性良好，粒径为10nm左右的纳米氧化锌，过程可控性好，简单易行。     

热分析联用技术在含能材料热分析研究中的应用进展

热分析联用分析技术包括同步联用技术、串级联用技术和间断联用技术,常见的有热重-差示扫描量热联用（TG-DSC）、热重-红外/质谱联用（TG-FTIR/MS）、固相原位热红外检测技术（Thermolysis/RSFTIR）和热重-红外-质谱联用（TG-FTIR-MS）等,是研究含能材料热行为和分解机理的有效方法,对研究其燃烧和爆炸性能有重要意义。相较于单一的热分析技术,联用技术可以更加充分、高效和全面地评价含能材料热行为和热安定特性、揭示热分解机制。通过热分析联用技术全面深入研究含能材料的物化特性,对改善和提高其应用性能具有重要的现实意义和价值。本文全面综述了TG-DSC、TG-MS、TG-FTIR-MS、TG-FTIR-GC-MS和Thermolysis/RSFTIR热分析联用技术在含能材料研究中的应用进展,分析了其研究的相关内容、重要结果、特点及优势,并进行了相关展望,可开发高性能的计算分析软件,解决如质谱分析中重叠质谱峰的解析等问题,在热分析仪中引入新的扩展系统,拓展其应用范围,为新型含能材料的热分析研究提供技术上的支持。     

Thermal Evolution of Solid Products Derived from Germanium-Containing Preceramic Polymer

The products formed during thermolysis of poly(germasilethyne) have been studied within temperature range 20–1600°C by means of Raman spectroscopy, XRD and EDS analysis, and SEM analysis. The evolution of solid products derived from poly(germasilethyne) as a function of heat-treatment temperature passes through several stages. At earlier stages the cross-linking of polymer molecules and the formation of rigid three-dimensional network occur. The particularity of the first stage of thermal transformation of poly(germasilethyne) in comparison with silicon analogue is not only the formation of the skeleton in the solid phase but also the release of disordered carbon phase. The stage of intensive thermal decomposition of germanium-containing polymer includes the escape of gaseous products, the formation of strongly disordered carbon, amorphous covalent silicon–germanium-carbon network and germanium as inorganic phase (most likely Si_1–x–yGe_xC_y). High-temperature treatment results in the evaporation of germanium, the formation and ordering of carbon and -SiC phases. The presence of germanium in the products of thermolysis of polymer leads to a faster growth of the oxides during exposition of thermolyzed polymer to air at high temperatures.     

BACTERIAL MUTAGENICITY OF DICYCLOPENTA-FUSED PYRENE CONGENERS IN FVT-PYROLYSATES: PARTIAL COMBUSTION EXHAUST MIMICS

The mutagenicity response of well-characterized flash vacuum thermolysis (FVT) pyrolysates that contain cyclopenta[cd]pyrene (1) and 1-ethynylpyrene (1b) (pyrolysate I), the dicyclopentapyrene congeners dicyclopenta[cd,mn]- (2), dicyclopenta[cd,fg]- (3), or dicyclopenta[cd,jk]pyrene (4) and their related bis-ethynyl- (2b–4b) and monocyclopenta-ethynylpyrene (2a–4a) analogues (pyrolysates II–IV, respectively), or cyclopenta[cd]- (1) and the three dicyclopentapyrenes (2–4) (pyrolysate V), respectively, was assessed using the standard protocol outlined by Ames et al. (Salmonella typhimurium strain TA98 ± S9-mix 4% (v/v)). It is shown that the mutagenic activity of the pyrolysates deviates from the weighed sum of the activity of the individual pyrolysate constituents. Hence, FVT-pyrolysates are proposed as model mixtures, that is, as partial combustion exhaust mimics, to establish and evaluate interactions (additive, synergistic, or antagonistic effects) that may occur among the constituents and affect the global mutagenicity response.     

Werner-type metal complexes of potato starch

It was shown that potato starch formed Werner‐type complexes. In these complexes a metal atom is ligated by the lone electron pairs of hydroxyl groups from d ‐glucose units and phosphate groups in starch. Acetate, chloride and nitrate were counter‐ions to the transition metal atoms. The metal cations bound preferentially to the phosphoric acid moiety of amylopectin, but secondarily they were co‐ordinated by the hydroxyl groups of the d ‐glucose units. This resulted in the formation of clathrate cages in which a significant number of the water molecules were trapped. Such structures were able to co‐ordinate further metal cations. Only Mn(II) and Co(II) ions, with acetate counter‐ions, neither formed clathrate cages nor were co‐ordinated by the hydroxyl groups of the d ‐glucose of starch.     

聚氨酯的化学降解

介绍了聚氨酯（PU）的水解、热降解、热氧化降解和紫外线降解的反应机理。PU的水解主要发生在酯基上，PU的热降解通常在氨基甲酸酯基上产生，PU的热氧化降解作用于醚基上，PU的紫外线降解在氨基甲酸酯基上断裂。芳香二异氰酸酯合成的PU在紫外线照射下，生成酯式结构，导致PU变黄。同时还指出了添加稳定剂可改善聚氨酯的稳定性。